The invention relates to a permanent-magnet excited synchronous with tooth coils in a stator and with a rotor.
Permanent-magnet excited synchronous motors of a type involved here experience torque oscillations. A skew of the rotor or stator by a slot pitch, as described, for example, for conventional motors in EP 0 545 060 B1, cannot be used in electric motors with concentric winding, i.e., tooth coils and a small number of slots, because this would exceedingly reduce the torque.
In electric motors with conventional windings, i.e., windings fabricated in drawing technique and with a relatively large slot number, a skew of approximately one slot pitch is typically applied.
Attempts have been made to reduce torque oscillations in electric motors with tooth coils by constructing the magnets in a particular shape. A disadvantage associated therewith is however the increase in manufacturing costs to construct magnets with a particular shape.